Automatic choke



Filed April 29 195s 5 SheetsSheet 1 66 I I I ll Ii 36 Z4 J y l l n 64 65 y/d g /z l 4e INVENTOR. 4lfit7P7/rf M44445? 1958 A. H. WINKLER 2,833,529

AUTOMATIC. CHOKE Filed April 29, 1955 s Sheets-Sheet 2 INVENTOR. 41551? 1% M/VAZZR y 6, 1958 A. H. WINKLER 2,833,529

AUTOMATIC CHOKE Filed April 29, 1955 3 Sheets-Sheet 3 IN V EN TOR.

United States Patent 6 AUTOMATIC CHOKE Albert H. Winkler, Elmira, N. Y., assignor to Bendix AviationCorporation, South Ben'd, Ind., a corporation of Delaware Application April 29, 1955, Serial No. 504,937

Claims. (Cl. 261-62) This invention relates to carburetors for internal combustion engines and more particularly to means for automatically controlling thecarburetor choke valve to vary the fuel-air mixture ratio in accordance to the requirement of the engine under various operating conditions.

During engine starting and warm up it is desirable to provide the engine with a rich fuel-air mixture. The degree of desired richness varies with ambient temperature, the colder the temperature the richer the mixture desired. The degree of richness also varies as a function of throttle position, a richer mixture being desired for full throttle operation than for part throttle operation.

It has been previously proposed in an automatic choke construction to use a yieldable member or spring between a throttle linkage and choke lever to "compensate for variations in ambient temperature and throttle position during engine warm up. Such a construction is, shown in copending U. S. application Serial No. 478,065, filed December 28, 1954, now Pat. No. 2,7865667, dated March 26, 1957, in the name of RobertW. Sutton and assigned to the assignee of the present application. The construction shown in this copending application has operated satisfactorily in commercial use, yet in some instances a greater degree of accuracy or fineness of control is required in rendering the compensating yieldable means ineffective at a predetermined degree of throttle opening.

Accordingly, it is a principal object of the present invention to provide in an automatic choke a control device for removing the compensating spring from effective position at an accurately controlled predetermined position of the throttle.

It is a further object of the invention to provide an improved device for exercising a more accurate control of the compensating spring in an automatic choke which minimizes spring fatigue.

Other objects and disadvantages will be readily apparent in the following detailed description taken in connection with the appended drawings in which:

Figure 1 is a top view of a carburetor embodying my invention;

Figure 2 is an enlarged top view of a choke control device shown in Figure 1' with the cover broken away;

Figures 3 and 4 are views of the interior of one embodiment of the choke device illustrating a position of the elements during various-conditions of engine operation;

Figures 5 and 6 are views of the interior of another embodiment of the choke control device illustrating the position of elements during various conditions of engine operation. 7

Referring now to the drawings, numeral 10 designates a carburetor having a choke valve 12 and a throttle valve 14 mounted in an induction passage 16 on shafts 18 and 20 respectively. The throttle shaft is journaled in a throttle body 22 and extends at one end into a choke control housing 24 which is cast integrally with said body. A throttle lever 26 is secured to the throttle 30 is weighted as at 34 to assume the slow idle position.

Shaft 32 is connected to choke shaft 18 by a linkage 36 and is adapted for rotation therewith. An intermediate lever 38 is secured to shaft 32 and is formed with a turned over portion 40 which is adapted. to form a one way connection between said lever and fast idle cam. Lever 38 is also provided with a projecting finger 42 adapted for engagement with hooked endof thermostat 44 which is secured at its other end in a cover member 46. When cold, the thermostat urges lever 38 in a counterclockwise direction to move cam 30 tothe fast idle position.

A torsion spring 48 is looped about throttle shaft 20 and is formed with arms 56 and 52 adapted for engage ment with a wall of the housing 24 and a stop member 54 respectively. Thermostat 44 urges a finger 56'on intermediate lever 38 into engagement with spring arm 52 which yieldingly opposes the closing of the choke valve. If the thermostat is cooled below a predetermined temperature the force of the thermostat will exceed that of the spring arm'52 and the choke valve will be moved toward closed position. A lug 58 on throttle lever 26 is adapted to form a one Way lost motion connection with spring arm 52 to positively move said arm away from the finger 56 when the throttle valve has been opened a predetermined amount. A lug 60 on the throttle lever is adapted to engage the finger 62 on, the intermediate lever 38 so as to provide a conventional means for unloading the carburetor.

Cover member 46 is adapted to be connected with a source of heated air (not shown) througha conduit 64. The interior of housing 24 is adapted to be connected to the induction passage posterior the throttle valve by a suitable conduit (not shown), The remainder of the.

carburetor structure is conventional and includes a fuel inlet passage 66, a throttle arm 68 adapted for connection to the usual accelerator pedal (not shown), and a dashpot 70 for retarding the closing movement of said throttle arm.

In the operation of the embodiment described thus far, the various elements of the automatic choke control device assume the position shown in Figure 3 where the throttle is in the fast idle position and lug 58 on the throttle lever 26 has been rotated out of engagement with the spring leaving stop member 54 to restrain further movement of the spring. In this position lug 28 prevents the further closing of the choke. As the throttle is opened lug 28 is disengaged from the fast idle cam 30 leaving spring arm 52 together with the force of air flow through the induction passage to balance the force of thermostat 44. At a predetermined degree of throttle opening, lug 58 picks up spring arm 52 moving it out of engagement with stop member 54. Continued movement of the throttle towardopened position renders spring arm 52 progressively less effective until at a predetermined value of throttle opening spring arm 52 is moved completely out of the path of finger 56 whereby the spring arm 52 is rendered completely inefiective to oppose the closing movement of the choke.

In Figure 4 the elements are illustrated in the wide open throttle and choke position where the spring is ineffective and the choke valve is controlled only by the thermostat 44 and air flow on the unbalanced surface of the choke valve.

It is to be noted that the operation of the device would remain unchanged if the stop member 54 were removed and the spring 48 calibrated to assume the position shown in Figure 3 when unrestrained by lug 58.

In the embodiment shown in Figures 5 and 6 the structure is intended to be identical to the previous embodiissub'stantially identical to the previous embodiment with the exception that lug 72 carries arm 50' of the spring for movement with the throttle lever so as to keep the flexing of the spring at a minimum. This construction reduces fatigue and lengthens the life of the spring.

In each of the embodiments there is shown a positively actuatedmeans for accurately controlling the eflfectiveness of the. automatic choke compensatingspring 48 or 48, The relative location of the various parts may be 1 varied in difierentapplications to vary the precise point in the opening of the throttle that the compensating spring is rendered ineffective.

1 Thedetails of the arrangement shown and described are by Way. of example only and may be varied to meet specific conditions within the teaching of the invention.

l. A choke control device for a carburetor having a throttle and a choke valve comprising a housing, an abutmentin said housing, a lever in said housing operatively connected to said choke valve, a spring stressed between said housing and abutment adapted to yieldingly engage ,saidlever to oppose the closing of said:choke valve, and a lever operatively connected to said throttle and having a one way connection with said spring to disengagesaidspring and choke lever at a predetermined degree of throttle opening.

2. A choke control device for a carburetor having a throttle valve, a choke valve and shaft for said throttle valve comprising a housing, a lever in said housing operatively connectedto said choke valve, a torsion spring encircling said throttle shaft adapted at one. end to engage the housing and at the other end to engage said lever to oppose the closing of said choke valve, and a lever operatively connected to said throttle shaft formed to disengage said spring and choke lever at a predetermined degree of throttle opening.

3. A choke control device for a carburetor having a throttle valve, a choke valve and shaft for said throttle valve comprising a housing, an abutment in said housing, a lever in said housing operatively connected to said choke valve, a torsion spring encircling said throttle shaft, means urging said spring into engagement with said abutment whereby saidspring is in a position to engage said choke lever to oppose the closing of said choke valve, and means operatively connected to said throttle shaft formed to disengage said spring and-abutment when said throttle valve is opened a predetermined amount.

4. A choke control device for a carburetor having a throttle and a choke valve comprising a housing, a lever in said housing operatively connected to said choke valve,

aispring stressed between said housing and said lever to oppose the closing of said choke valve, and a lever operatively connected to said throttle and having a one-way connection with said spring to disengage said spring from said choke lever at a predetermined degree of throttle opening.

'said throttle valve formed to disengage said spring from said lever when said throttle is opened a predetermined degree.

References Cited in the file of this patent 1 UNITED STATES PATENTS 2,124,778 Hunt July 26, 1938 2,215,682 Winkler Sept. 24, 1940 Hennemann Aug. 26, 1947 

